1. Field of the Invention
The present invention relates to the technical field of image positioning system and, more particularly, to a coordinate positioning system and method with in-the-air positioning function.
2. Description of Related Art
In the positioning system of a typical game host for CRT screen, a light gun is equipped with a sensor to receive a signal in a local region aimed by the light gun. Thus, the sensor of the light gun can sense the signal when the CRT screen scans the local region aimed by the light gun. In addition, the light gun contains a timer to count time as soon as a frame displayed on the CRT screen is scanned at a start of the left upper corner, and the timer is restarted when the entire frame is scanned completely. When a game player aims the light gun at a target, the timer can record the time of scanning from the left upper corner to the target by a scan signal of the CRT screen, and accordingly the coordinate of the target can be computed. However, such a positioning system is likely to cause a significant error. Further, due to the principle of the interlaced frame display in the CRT screen, and the positioning system for the CRT screen is not suitable for the LCD TV and requires a redesign.
FIG. 1 is a schematic view of a typical image positioning system 100, which consists of an image display 110 and an image sensor 120. The image display 110 includes LEDs 112, 113 and 114 to be assigned with the identification codes “first”, “second” and “third” respectively, and to be isogonally distributed on a plane 111. The image sensor 120 includes a photosensor 121 formed by CMOS.
The photosensor 121 detects and receives the light sources of the LEDs 112, 113 and 114, and finds the virtual coordinate 140 aimed by the image sensor 120 according to the coordinates of the LEDs 112, 113 and 114.
The LEDs 112 to 114 can be implemented on the corners of a large projector or LCD screen. In this case, the plane 111 can be an imaging plane of a screen, and the image sensor 120 can be used as a projection pen or mouse by an operator. When the operator aims the image sensor 120 at the screen, the virtual coordinate 140 aimed by the image sensor 120 is the position of a light spot indicated by the projector pen or the position of a cursor manipulated by the mouse. The identification codes of the LEDs 112, 113 and 114 are identified, and the virtual coordinate 140 is well computed according to the coordinates of the LEDs sequentially corresponding to the respective identification codes.
The image sensor 120 detects the LEDs 112, 113 and 114 and produces a mapping image, as shown in FIG. 2. For a typical condition, the image sensor 120 identifies the identification codes of the LEDs 112, 113 and 114 according to the coordinates, which starts at the right-down corner in the reverse clock direction to sequentially find the codes “first”, “second” and “third”. For convenient description, the following is referred to as a first LED 112, a second LED 113 and a third LED 114. When the image sensor 120 rotates 120 degrees with respect to the arrow 150 shown in FIG. 1, a mapped image is produced shown in FIG. 3. In this case, FIGS. 2 and 3 have same mapped images, and the identification codes of the first to third LEDs 112 to 114 are mistakenly identified when the identification is taken from the right down corner in the reverse clock direction as usual. For example, after the 120-degree rotation, the identification code of the third LED 114 is shifted to the right down corner and mistaken as “first”. Similarly, the identification code of the LED 112 is mistaken as “second”, and the identification code of the LED 113 is mistaken as “third”. Therefore, the typical positioning system cannot correctly obtain the corresponding virtual coordinate 140 when the image sensor 120 is rotated by a certain angle.
Accordingly, another prior art applies at least three light-producible positioning units that locate in different lines and have different identification codes, and an auxiliary unit. The auxiliary unit locates on the connection of the first positioning unit and the second positioning unit. An image sensor receives the light produced respectively by the first positioning unit, the second positioning unit, the third positioning unit and the auxiliary unit, and accordingly obtains a space coordinate. The identification codes of the positioning units are obtained according to the space relation of the positioning units to the auxiliary unit. The coordinates of the positioning units sequentially corresponding to the identification codes are used to properly perform the directional positioning procedure. Such a way can avoid the problem that the typical positioning system cannot accurately obtain the virtual coordinate 140 pointed by the image sensor 120, but it needs to implement a plurality of the positioning and auxiliary units on the screen of the display, which affects the appearance of the screen and the imaging on the screen.
FIG. 4 is a block diagram of an image positioning system disclosed in US Patent Publication No. 20070052177 entitled “Game operating device”. In FIG. 4, the system includes an infrared imaging device 56 and an image processing circuit 76. The image processing circuit 76 processes the image data obtained by the infrared imaging device 56. The infrared imaging device 56 includes a solid imaging element 561, an infrared filter 562 and a lens 563. The infrared imaging device 56 senses a high-intensity portion, detects the portion's center-of-gravity position and area, and outputs the corresponding data. The image processing circuit 76 outputs the corresponding data to a processor 66. The acceleration sensor 68 outputs the two-axis or three-axis acceleration data to the processor 68.
FIG. 5 is a schematic view of using the image positioning system of FIG. 4. As shown in FIG. 5, the LED modules 920A, 920B are implemented on top of a CRT TV 910. The infrared imaging device 56 senses the LED modules 920A and 920B, detects the center-of-gravity positions and areas, and outputs the corresponding data. A remote control 900 transmits the corresponding data and the two-axis or three-axis acceleration data to a game machine 930 through a wireless module 70. The game machine 930 accordingly computes the position of the remote control 900. However, the positioning system requires an additional acceleration sensor 68, which increases the hardware cost.
Therefore, it is desirable to provide an improved positioning system and method to mitigate and/or obviate the aforementioned problems.